Sorry for dragging this old thread in from the mud, but if you're on Amiga the best thing to use for this purpose is MaPuS, which is how the banners ended up in the DMS-files in the first place. Or if you feel hacky you could just load the DMS-file straight in to CygnusEd and check around the end of the file which is usually where the FILE_ID.DIZ and board ads sits.
You probably solved it all already, but I posted for other people who might try to find the same info. (:
3 years later!